Aminoresin-silica microcomposites

ABSTRACT

1. A COPOLYMERIZED COMPOSITE COMPRISING POLYSILIC ACID AND POLYMERIC AMINORESIN; SAID COMPOSITE HAVING A PARTICLE SIZE RANGE FROM 1U TO 50U; SAID COPOLYMERIZED COMPOSITE CONTAINING FROM 40% TO 99% OF POLYSILICIC ACID, CALCULATED AS SILICA BY WEIGHT, THE REMAINDER BEING THE AMINORESIN POLYMER, SAID AMINORESIN POLYMER CONTAINING 0.5-2.0 MOLES OF FORMALDEHYDE FOR EACH MOLE OF AMINO EMPLOYED.

United States Patent 3,845,006 AMINORESIN-SILICA MICROCOMPOSITES ModestoErneta, Princeton Junction, N.J., assignor to NL Industries, Inc., NewYork, NY.

No Drawing. Filed May 7, 1973, Ser. No. 358,035 Int. Cl. C08g 51/04 US.Cl. 260-37 N 9 Claims ABSTRACT OF THE DISCLOSURE Spheroidal shapedparticles of silica-aminoresin polymeric composites have been producedwhich possess particles having a range from I to 50;. The compositescontain from 40% to 99% silica, the remainder being an aminoresin. Theparticles are more or less spheroidal in shape and appear to have largeholes where the spheres have collapsed. These compositions are useful infilms and paper coatings.

BACKGROUND OF THE INVENTION Various types of microspheres ormicrocapsules have been produced for a variety of uses. Among thosewhich are related to the product of the instant invention areureaformaldehyde micro-particles having individual particle sizesranging from 0.05 1. to 0.1 which are formed as loosely adherentclusters having a cluster size from 1p. to 10 Such products have beensuggested for use as opacifying agents for paint, paper and the like.These products have been used with limited success.

SUMMARY OF THE INVENTION Spheroidal shaped particles ofsilica-aminoresin polymeric composites have been prepared. Theseparticles have an average size range from lg to 50 with a surface arearange from 10 to 300 m. g. The composites have a composition of 40% to99% silica, the remainder being the aminoresin. These particles appearto have been formed first as spheres which upon drying formed holes inthe side walls of the sphere. The dried products appear as spheroidalparticles having collapsed side walls.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The amino resins used in theinstant invention include amino-formaldehyde condensation products ofurea, melamine, aniline, guanidine and thiourea. These aminoresins areformed and polymerized in the presence of polysilicic acid which upondrying forms silica-aminoresin polymerized composite. The amounts of theamino group and the formaldehyde employed should be from 0.5 to 2.0moles of formaldehyde for each part of the amino group used.

In preparing these compositions the following general procedure isemployed:

A solution of polysilicic acid is placed in a container and withagitation, a solution of a prepolymer of an amino-formaldehyde resin isthen added to the polysilicic acid solution.

The mixture is then preferably spray dried at elevated temperatures toform the spheroidal shaped polymerized composites of silica andaminoresin. If spray drying is not used, the mixture is heated to 50 C.to boiling to polymerize the composite and the precipitated product isremoved.

It has been found that the amount of silica present in the compositeshould fall within the range of 40% to 99%,

3,845,006 Patented Oct. 29, 1974 the remainder being the aminoresin. Allof the percentages are expressed on a weight basis. When the productsare used for opacification in paper, the composite should contain silicain the amounts specified to produce superior hiding in the paperproduct.

The composite particles produced have been found to contain a surfacearea which falls within the range of from 10 to 300 mP/g.

In order to describe the instant invention in more detail, the followingexamples are presented:

Example 1 This example is presented to show the preparation of highlyuniform silica-amino resin microspheres containing 69% silica, 23% ureaformaldehyde, and 8% water. silica and 25% urea formaldehyde on a drybasis) all of the percentages expressed on a weight basis.

1360 lbs. of an aqueous solution of polysilicic acid with a Si0 contentof 5.5% by weight were placed in a container and agitated vigorously.

To this solution were added 38.5 lbs. of an aqueous solution of ureaformaldehyde resin containing 65% by weight solids.

This solution was then pumped to a spray dryer. The spray dryer operatedwith an air inlet of 700 F. and with an air outlet of 200 F. The productwas collected at the bottom of the dryer as a white free flowing powderymaterial. This material was comprised of spheroidal hollow particleshaving a particle size range of 5;; to 40p. with a surface area of 270m. /gm. and a bulk density of .6 gm./cc. A particle analysis shows theparticles contained by Weight 69% SiO 23% urea formaldehyde, and 8% H O.The operational details are recorded in the table.

When 5% by Weight of these particles were used in conjunction with 5% byweight of TiO in a paper composition, it was found that the bulk densityof the paper decreased with only a slight decrease in opacity oversimilar paper which contained 10% pigment by weight of TiO Instead ofspray drying the mixture may be heated from 50 C. to boiling toprecipitate and polymerize the composition if desired.

Examples 2-3 These examples are presented to show varying weight ratiosof Slo to urea formaldehyde. In Example 2, the dry product contained95.4% by weight SiO and 4.6% by Weight urea formaldehyde. In Example 3the percent by weights were 47.6% SiO and 52.4% urea formaldehyde (thepercentages express on a dry weight basis).

The operational details are recorded in the table.

Examples 4-5 These examples are presented to show a product whichcontained amino resins other than urea formaldehyde. Melamineformaldehyde was used in Example 4, and thiourea formaldehyde was usedin Example 5. The operational details are recorded in the table.

When the products of Examples 2-5 were used in paper along with TiO (5%spheroidal particles and 5% TiO the bulk density of the paper decreasedwith only a slight decrease in opacity when compared to paper whichcontained 10% TiO While this invention has been described andillustrated by the examples shown, it is not intended to be strictlylimited thereto, and other variations and modifications aminoresin, saidaminoresin being amino-formaldehyde may be employed within the scope ofthe following claims: and containing 0.5-2.0 moles of formaldehyde foreach TABLE Example 1 2 3 4 5 Percent by weight SiO 75 95.4- 47.6--.75.5- 75.

Percent by weight amino resin 2.4

Type of amino resin Amt. of polysilicic acid solution (110.) 1,360 8.816.30 6.6 6. Percent by weight SiO in polysilicic acid 5.5-- Amt. aminoresin solution (1b.) Percent solids in amino resin solution Air inletF.) Air outlet F.) Particle range (1-1.) Surface area (n1 ./gm.) Bulkdensity (gm./cc.)

* On a dry basis.

What is claimed is: mole of amino employed, said copolymerizedcomposite 1. A copolymerized composite comprising polysilicic producedhaving a particle size range from 1, to 5011.. acid and polymericaminoresin; said composite having a 6. Process according to Claim 5 inwhich the aminoparticle size range from 1,41. to 50 said copolymerizedresin is urea formaldehyde. composite containing from 40% to 99% ofpolysilicic 7. Process according to Claim 5 in which the aminoacid,calculated as silica by weight, the remainder being resin used ismelamine formaldehyde. the aminoresin polymer, said aminoresin polymercontain- 3, Process according to Cl im 5 in which th a inoing 0.5-2.0moles of formaldehyde for each mole of amino resin used is thioureaformaldehyde, p y 9. Process according to Claim 5 in which thecopolymnfi- O PPP Z F f i d ggyg Claim 1 1n Whlch the erized compositionis formed by spray drying the mixture a 1n resln 18 ea orma e. of 1 d 13. Composition according to Claim 1 in which the Sal prep ymer an Sal Poyslhclc and aminoresin is melamine formaldehyde. References Cited 4.Composition according to Claim 1 in which the aminoresin is thioureaformaldehyde. UNITED STATES PATENTS 5. Process for producing acopolymerized composite of g t Y et -1 aminoresin and 01 silicic acidwhich com rises admixin ers cm at a 9 p y P g 2,408,654 10/1946 Kirk106287 X s an aqueous solution of an aminoresin prepolymer and a watersolution of polysilicic acid and heating the mixture 35 to 50 C. toboiling to form a copolymerized composite of MORRIS LIEBMAN 'PnmaryExammer said prepolymer and said polysilicic acid and recovering FARR:Assistant Examiner said copolymerized composite therefrom, the amount ofpolysilicic acid employed being from 40% to 99% of the mixture,calculated as SiO the remainder being the 40 106198, 287 S, 308 N; 26039SB

1. A COPOLYMERIZED COMPOSITE COMPRISING POLYSILIC ACID AND POLYMERICAMINORESIN; SAID COMPOSITE HAVING A PARTICLE SIZE RANGE FROM 1U TO 50U;SAID COPOLYMERIZED COMPOSITE CONTAINING FROM 40% TO 99% OF POLYSILICICACID, CALCULATED AS SILICA BY WEIGHT, THE REMAINDER BEING THE AMINORESINPOLYMER, SAID AMINORESIN POLYMER CONTAINING 0.5-2.0 MOLES OFFORMALDEHYDE FOR EACH MOLE OF AMINO EMPLOYED.